An automatic testing machine (ATM) operates in a production environment to rapidly and accurately test the operation and performance of various types of devices under test (DUT), including RF communication devices. The DUTs could be a finished product or a component of a larger system.
The ATM is programmed to perform various tests on the DUT automatically. For example, RF signals are transmitted to a finished cellular telephone DUT to determine if the telephone activates. Other tests could include environmental tests, such as temperature or vibration tests.
Depending upon the nature and number of the tests being performed, the testing may last from a couple of milliseconds to several minutes. The information from the testing is compared with expected test results. If there is some defect so that the DUT falls below specifications, the ATM will designate the DUT as failed, either by marking the DUT, placing the DUT in a failure area, or indicating the failure to an operator.
The ATM is then loaded with the next DUT, either manually or automatically, and the testing procedure is repeated for this DUT. This test information can be used to evaluate the fabrication process for possible changes, as well as to perform failure analysis on individual failed devices.
Typically, each ATM is designed to perform a specific class of tests on the DUT, and are not able to perform other classes of tests. For example, a vibration ATM may not be able to perform electrical signal tests. However, different types of DUTs may require the same tests to be performed. For example, all types of microcomputer chips are tested for electronic performance characteristics, but different chips will have different locations for power, inputs and outputs. ATMs are made flexible by the use of test fixtures. The test fixture provides an interface between the device under test DUT and the ATM. Thus, a single ATM can perform tests on different types of devices when connected via different fixtures.
Fixtures typically have a drawer mechanism, which opens up and allows the DUT to be placed inside the fixture. The fixture may have an RF cable that fixedly mounted within the fixture, and has a length of cable which is connected to the drawer mechanism. The cable terminates at a connector which is pneumatically engaged on the telephone. Some fixtures have RF probe connector mounted inside the fixture which makes contact with an antenna element on the DUT. Thus, contact is not made until the drawer is closed. Thus, RF connections, pneumatic actuators, and their air supplies, are hardwired or constructed directly onto the drawer mechanism. The hardwired aspects makes fixtures extremely difficult to reconfigure, because all the of the fixture elements are integrally built into the fixture.
Moreover, fixtures tend to be large and bulky. Also, they have numerous connections to the ATM for the required resources to allow testing, e.g. power, electronic signals, RF signals, and pneumatic air pressure. Thus changing fixtures is time consuming, as each individual connection to the ATM must be separated, the current fixture removed, and then the new fixture installed. During the replacement process, the production line is shut down, which results in lost production time. If the fixture needs to be repaired, then this process must be undertaken, and the lost production time is unavoidable. However, if the fixture is to be changed merely to accommodate a different DUT, then the lost production time can be mitigated by using an adapter. An adapter is a DUT holder that is coupled to the fixture on the drawer mechanism. The adapter is customized to hold the specific type of DUT. If a different DUT needs to be tested then the adapter in the fixture is swapped for the proper adapter.
However, the adapter does not have any continuous or semi-permanent RF connections, as RF connection is only made when the drawer mechanism is closed. The lack of continuous connection by itself is not a problem, since RF testing cannot begin until the RF sealed drawer is closed. The problem is the wear on the connectors from many cycles of the drawer being opened and closed. Typically, one end of a connector is located at the back of the adapter, and the other end of the connector is located inside of the fixture mount, thus, when the drawer is closed, the connection would be made. The RF connection degrades based on the number of cycles, and the degradation is very significant. One form of degradation is where the plating on the mating parts wears from continual cycles of making and breaking contact. Another form occurs where the connectors have a soft plastic core used to form a dielectric layer between the two conductors of the coaxial cable. The plastic core would crack or degrade from the flexings caused by cycles of making and breaking contact. Consequently, the connectors do not last very long, and significant production downtime is incurred for replacing the connectors.
Therefore, there is a need in the art for a system and method that allows for the rapid and reliable conversion of an ATM to test a different DUT, and at the same time reduce the wear on RF connections from opening and closing the drawer mechanism of the fixture in a production environment.